Comma Splices and Run-on Sentences

Next, read this lecture on how to fix comma splices and run-on sentences, and then complete the practice activities in which you correctly punctuate sentences to avoid the errors of comma splices and run-ons. Once you complete the practice activities, check your answers against the Answer Key. You will learn more about using commas and other punctuation to craft complete sentences in Unit 3.

A COMMA SPLICE occurs when a comma separates clauses that can each stand alone as a sentence.

Example: Albert Einstein worked as a clerkhe was a brilliant scientist.

The comma separates two complete sentences, creating a comma splice. Comma splices make sentences difficult to understand because ideas are not separated the way that they should be.


Another common error is the RUN-ON SENTENCE. This error occurs when two or more independent clauses that could each stand alone as a sentence are joined together. The clauses have no punctuation or linking words in between them. As a result, the sentence keeps on going after it should have ended, making it difficult to understand.

Example: Albert Einstein worked as a clerk he was a brilliant scientist.

This sentence joins two independent clauses without punctuation or linking words (conjunctions), creating a RUN-ON.




Coordinating conjunctions: for, and, nor, but, or, yet, so

Some students find the acronym FANBOYS helps them to remember these. A coordinating conjunction combines ideas in a sentence, giving the ideas equal emphasis.


Subordinating conjunctions: There are many, but here are some common ones:

after, although, as, because, before, even though, unless, when, where, while, until, in order that, if, since, once, etc. 

A subordinating conjunction emphasizes one idea more than another.


Conjunctive adverbs: There are many, but here are some common ones:

however, furthermore, therefore, likewise, accordingly, similarly, consequently, moreover, etc. 

A conjunctive adverb shows the relationship between independent clauses.


There are several ways to fix COMMA SPLICES and RUN-ON SENTENCES:

  • Substitute a period for the comma to create two separate sentences.
  • Put a coordinating conjunction – for, and, nor, but, or, yet, so – after the comma.
  • Use a subordinating conjunction to link the independent clauses.
  • Change the comma to a semicolon.
  • Use a semicolon with a conjunctive adverb to show the relationship between the ideas in the two clauses.


Remember, not all methods will fix every COMMA SPLICE or RUN-ON. Some work better than others in certain situations.

Albert Einstein worked as a clerk. He was a brilliant scientist.

Albert Einstein worked as a clerk, but he was a brilliant scientist.

Although Albert Einstein worked as a clerk, he was a brilliant scientist.

Albert Einstein worked as a clerk; he was a brilliant scientist.

Albert Einstein worked as a clerk; nevertheless, he was a brilliant scientist.

All of the above sentences are correct; however, you should know that if you use a semicolon to join independent clauses, the ideas in them should be closely related. For example, since the following two sentences are unrelated, linking them with a semicolon is incorrect:

I am trying to decide on a college major; I hope the dorms have a laundry facility.

Such a sentence is confusing because the two ideas are not closely related.


Practice I: Punctuate the following sentences using the comma rules:

  1. When the 1989 earthquake shook Santa Cruz Peter decided to move back to New York.
  2. Peter is majoring in Elementary Education isn't that right?
  3. Tim made a three-layer chocolate cake Nina tuned up the car.
  4. Lars has been studying Chinese for more than ten years he's never had the opportunity to visit China.
  5. She was on time for the date when she arrived he wasn't there.


Practice II: Correct FIVE of the following comma splices and run-on sentences by adding a period. Correct the other FIVE by using a comma and a coordinating conjunction (for, and, nor, but, or, yet, so).

  1. She doubted the value of yoga she decided to try it just once.
  2. I asked the guard for directions, she told me what time it was.
  3. California is suffering an energy crisis, everyone needs to conserve.
  4. Ruby is tiny she is less than five feet tall and weighs ninety-five pounds.
  5. First we hiked in the forest, we drove up to Mount Baker.
  6. Television commercials can have an adverse impact on children, it's hard to prevent them from watching TV.
  7. I loved the movie, most of my friends hated it.
  8. He has never won a dime playing the lottery every week he spends ten dollars on tickets.
  9. My high school adviser was close to me she was almost my best friend.
  10. Writing is sending, reading is receiving.

Source: Washington State Board for Community and Technical Colleges,
Creative Commons License This work is licensed under a Creative Commons Attribution 3.0 License.

Last modified: Friday, January 8, 2021, 1:02 PM